" Does anyone know if the drawer inserts are solid 304 stainless? "

What inserts? Whose the manufacturer? What else would they be if not solid stainless?

There a huge difference between 314 marine grade stainless that won’t rust or regular stainless that will rust . I need 314 for an outdoor kitchen on the water in Florida.

Correct. Are you asking whether all cabinetry/appliances made of stainless steel are made of 314 austentic steel? Probably not. I’m sure you know that 314 stainless is corrosion resistant. That doesn’t mean it ”won’t rust” but that it is less prone to rusting. 316 stainless steel has up to 3% Molybdenum and is even more corrosion resistant that 314. If you want corrosion resistant stainless steel cabinets you have to buy them from a brand that tells you what material they use.

Stainless does not mean it never rusts What do you mean by inserts maybe show what that is. I have all drwer inserts that are a really hard strong plastic so not sure what inserts you have.