A method for making an injection molded multilayer polymer pump diaphragm having one side resistant to chemicals. The method can include injecting molten polymer material of a first type having chemical resistance properties into a first pump diaphragm mold cavity to produce a first pump diaphragm layer; curing the first pump diaphragm layer; applying an adhesive to one side of the first pump diaphragm layer; placing the first pump diaphragm layer in a second pump diaphragm mold cavity sized to receive an amount of a second type of polymer material against the adhesive painted side of the first pump diaphragm layer; injecting molten polymer material of the second type into the second pump diaphragm mold cavity into contact with the adhesive to produce a second pump diaphragm layer adhered to first pump diaphragm layer; and curing the second pump diaphragm layer such that said first and second pump diaphragm layers adhere together to form a pump diaphragm having one side which is resistant to chemicals.