I agree with Ann about using washables. That will likely stop the eating. A member here handcrafts a very popular brand: T. Bumpkins & Co. Her website where you can order:
Washable and reusable dog and puppy pee pads, belly bands, and diapers by T. Bumpkins & Co.
It is unusual to want to eat pee, but maybe your pup is concerned about leaving it. Sometimes Max will wrap up his piddle pad, usually after a morning pee, which tends to have a stronger scent.