Q:

Which verses for god indra in vedas mention him as friend of all human beings?

Which verses for god indra in vedas mention him as friend of all human beings? 
His myths and adventures in the
Vedic literature are numerous,
ranging from harnessing the
rains, cutting through mountains
to help rivers flow, helping land
becoming fertile, unleashing sun
by defeating the clouds, warming
the land by overcoming the
winter forces, winning the light
and dawn for mankind, putting
milk in the cows, rejuvenating
the immobile into something
mobile and prosperous, and in
general, he is depicted as
removing any and all sorts of
obstacles to human progress.

sourse:— https://en.wikipedia.org/wiki/Indra
The hymns of Rigveda declare
  him to be the "king that moves
  and moves not", the friend of
  mankind who holds the different
  tribes on earth together.

So the question is what verses call indra as he friend of mankind who holds the different tribes on earth together.

A:

It's the translation of 15th Sloka of 32th Sukta of 1st Mandala of Rigveda:

इन्द्रो यातोऽवसितस्य राजा शमस्य च शृङ्गिणो वज्रबाहुः।
  सेदु राजा क्षयति चर्षणीनामरान्न नेमिः परि ता बभूव॥ १.०३२.१५
15 Indra is King of all that moves and moves not, of creatures tame and horned, the Thunder-wielder.
  Over all living men he rules as Sovran, containing all as spokes within the felly.

Actually the lines of Wikipedia you've mentioned referring to the citation of The Religion of the Ṛigveda, p 180:

Indra is king of that which moves and moves not,
  Of tame and horned creatures, too, bolt weaponed;
  Over the tribes of men he rules as monarch;
  As felly spokes, so holds he them together.

A:

There are many but I think Rigveda 4.25.4 (i.e. 4th Richa of 25 Sukta of 4th Mandala of Rigveda) is more appropriate as per your question. Here is the original Richa in Sanskrit with Hindi translation:

English Translation: (Source)

To him shall Agni Bhārata give shelter: long shall he look upon the Sun up-rising, Who sayeth, Let us press the juice for Indra, man's Friend, the Hero manliest of heroes.

Update as asked by Questioner
Here is the English translation of other related Richas of Rigveda from http://www.sacred-texts.com/ (Note: didn't verify with original Richas and their other translations, meaning of few Richas may vary.) :
1.101.1/2/3/4/5/6/7
1 SING, with oblation, praise to him who maketh glad, who with Ṛjiśvan drove the dusky brood away.
Fain for help, him the strong whose right hand wields the bolt, him girt by Maruts we invoke to be our Friend.
2 Indra, who with triumphant wrath smote Vyaṁsa down, and Śambara, and Pipru the unrighteous one;
Who extirpated Śuṣṇa the insatiate,—him girt by Maruts we invoke to be our Friend.
3 He whose great work of manly might is heaven and earth, and Varuṇa and Sūrya keep his holy law;
Indra, whose law the rivers follow as they flow,—him girt by Maruts we invoke to be our Friend.
4 He who is Lord and Master of the steeds and kine, honoured—the firm and sure—at every holy act;
Stayer even of the strong who pours no offering out,—him girt by Maruts we invoke to be our Friend.
5 He who is Lord of all the world that moves and breathes, who for the Brahman first before all found the Cows;
Indra who cast the Dasyus down beneath his feet,—him girt by Maruts we invoke to be our Friend.
6 Whom cowards must invoke and valiant men of war, invoked by those who conquer and by those who flee;
Indra, to whom all beings turn their constant thought,—him girt by Maruts we invoke to be our Friend.
7 Refulgent in the Rudras’ region he proceeds, and with the Rudras through the wide space speeds the Dame.
The hymn of praise extols Indra the far-renowned: him girt by Maruts we invoke to be our Friend.
1.129.4
4 We wish our Indra here that he may further you, the Friend, beloved of all, the very strong ally, in wars the very strong ally
In all encounters strengthen thou our prayer to be a help to us. No enemy—whom thou smitest down—subdueth thee, no enemy, whom thou smitest down.
1.173.10
10 Like men in rivalry extolling princes, our Friend be Indra, wielder of the thunder.
Like true friends of some city's lord within them held in good rule with sacrifice they help him.
1.178.2
2 Let not the Sovran Indra disappoint us in what shall bring both Sisters to our dwelling.
To him have run the quickly flowing waters. May Indra come to us with life and friendship.
2.31.3
3 Or may our Indra here, the Friend of all mankind, coming from heaven, most wise, girt by the Marut host,
Accompany, with aid untroubled by a foe, our car to mighty gain, to win the meed of strength.
3.43.2/4
2 Come our true Friend, passing by many people; come with thy two Bay Steeds to our devotions;
For these our hymns are calling thee, O Indra, hymns formed for praise, soliciting thy friendship.
4 Yea, let thy two Bay Stallions bear thee hither, well limbed and good to draw, thy dear companions.
Pleased with the corn-blent offering which we bring thee, may Indra, Friend, hear his friend's adoration.
4.16.9
9 Come, Maghavan, Friend of Man, to aid the singer imploring thee in battle for the sunlight.
Speed him with help in his inspired invokings: down sink the sorcerer, the prayerless Dasyu.
10 Come to our home resolved to slay the Dasyu: Kutsa longed eagerly to win thy friendship.
Alike in form ye both sate in his dwelling the faithful Lady was in doubt between you.
6.45.1
1 THAT Indra is our youthful Friend, who with his trusty guidance led
Turvaśa, Yadu from afar.
8.50.11
11 We count not then as sinners, nor as niggardly or foolish men,
When with the Soma juice which we have shed we make Indra, the Mighty One, our Friend.
8.82.3
3 This Indra is our gracious Friend. He sends us in a full broad stream
10.29.1/4/7
1 As sits the young bird on the tree rejoicing, ye, swift Pair, have been roused by clear
laudation,
Whose HeraldPriest- through many days is Indra, earths' Guardian, Friend of men, the best of
Heroes.
4 Indra, what fame hath one like thee mid heroes? With what plan wilt thou act? Why hast thou
sought us?
As a true Friend, WideStrider-! to sustain us, since food absorbs the thought of each among us.
7 They have poured out a bowl to him, to Indra, full of sweet juice, for faithful is his bounty.
Over earths' expanse hath he grown great by wisdom, the Friend of man, and by heroic exploits.
Riches in horses, kine, and corn.
Note: In Rigveda, such Richas are present for many other Gods too.

