Wales beat Fiji 48-19, scoring six tries in their opening game of the tournament on Monday, but they must beat Mike Ruddock's Ireland to set up a probable Pool decider against France next Tuesday.
Hayward said, "We are using the squad, but in a way that will add impact to our performance. The hooker and openside flanker positions are very competitive within the group. Elliot (Dee) came on and played well in the second half against Fiji and deserves a chance to start, while the third hooker, Scott Otten is on the bench and will no doubt make an impact when he comes on.
"Will Boyde and Scott Matthews put healthy pressure on each other for the No 7 shirt and Will will be fresher, having not played as many minutes in the last game, while Scott will be looking to create an impression when he comes off the bench.
"Joshua Adams put in a great shift when he came on against Fiji, his energy levels were outstanding, he put in a huge amount of work off the ball and that work rate will be vital against Ireland.
"I expect it to be a tight game. Our scrum won us the Six Nations game against the Irish in Athlone and we need to maintain the pressure in that area but we need to try and play some expansive rugby too. Ireland's scrum has improved, causing problems against the French, and the weather is very good at the moment so the conditions are set be different from that Six Nations game.
"It was very pleasing to produce a disciplined performance against Fiji and come away with a bonus point, but if we beat Ireland by a point, it will be a job well done."
The only player unavailable for this game is back row Ben Roach who received stitches to a deep cut to the head after scoring the last try of the game.
Wales team v Ireland (Pukekohe, Friday 6 June, 6.35am live on Sky Sports, extended highlights on S4C at 9.30pm):
Ashley Evans (Ospreys); Tyler Morgan (Dragons), Steffan Hughes (capt, Scarlets), Jack Dixon (Dragons), Joshua Adams (Scarlets); Angus O'Brien (Dragons), Luc Jones (Dragons); Nicky Smith (Ospreys), Elliot Dee (Dragons), Nicky Thomas (Ospreys), Joe Davies (Dragons), Rory Thornton (Ospreys), Olly Cracknell (RGC), Will Boyde (Carmarthen) James Benjamin (Dragons)
Replacements: Scott Otten (Ospreys), Luke Garratt (Dragons), Callum Lewis (Blues), Scott Andrews (Dragons), Scott Matthews (Dragons), Tom Williams (Blues), Ethan Davies (Dragons), Afon Bagshaw (RGC).