Zabaz the Glimmerwasp's replacement effect requires it to be on the battlefield to work. Notably, that means it won't increase the counters given by its own modular ability.

If this creature gets enough -1/-1 counters put on it to cause it to go to the graveyard, modular will put a number of +1/+1 counters on the target artifact creature equal to the number of +1/+1 counters on this creature before it left the battlefield.