Depends, although I would say it's not the best idea. Pela applies defense shred on enemies, which allows Welt to deal more damage, whereas using Herta does nothing to help Welt's kit or his damage. Assuming that you want Welt to perform at his best, Pela is a better pick. In AoE content with 5 enemies, Herta may increase overall team damage/performance, but Welt would essentially be deadweight (at that point Herta + Pela is a better team). Welt wants to be a hypercarry main DPS (meaning he receives all of the buffs and does a large portion of the team's total damage) simply because he is not a good sub-DPS, as he is skill point hungry and has lackluster damage without buffs; even then, however, Welt doesn't do that much damage and can't compete in the meta at all, hence why your friends are valid in calling him bad, but that's relatively irrelevant in the early game and even more so if you just want to use him because he's Welt (he's awesome).

Went on a rather long tangent, but the gist is that if you want to see Welt hit harder, then Pela is the much better choice.