A pump casing has a metallic band that defines a sidewall of the pump casing and having at least one tab projecting from a surface thereof or at least one opening. The pump casing also has first and second plates disposed opposite one another, with the metallic band being disposed there between, and with the first and second plates and the metallic band jointly defining a chamber of the pump casing. At least one of the first or second plates includes at least one tab or at least one opening respectively cooperating with the at least one opening or the at least one tab of the metallic band so as to retain a formed shape of the metallic band in the pump. The at least one opening may, for example, be a slot in the at least one of the first or second plates.