An improved self-priming, centrifugal pump arrangement for mixed-media flow includes a volute housing having a suction and a discharge, a volute scroll disposed within the volute housing, an impeller disposed within the volute scroll, a suction hopper and a discharge hopper within volute housing, a back cover and a wear plate attached to the volute housing. By optimizing the geometry of these internal components, noise is reduced, efficiency of the pump is improved, and the self-priming feature is maintained.