What size is the wire mesh? Measure the wire diameter, and the number of wires per inch. For a reference of how to measure the wire cloth, use this link: Belleville Wire Cloth
I would have to assume that the original wire mesh screen here is made of stainless steel to stay away from rust and corrosion as much as possible... Try ordering a piece from Mcmaster or your local hardware store as a replacement, should not cost you too much, just be careful because this stuff is sharp!