The aim of the invention is to provide a simple, smoothly running pump, especially a slurry pump, preferably for concrete, which comprises a driven rotor (4) rotating inside a housing (2). According to the invention, the rotor (4) is configured as a polygonal, prismatic body wherein at least the connecting lines of the corners of the base form an equilateral polygon. The rotor performs a rotational movement about its center axis on an orbit, the longitudinal edges of the prismatic body (4′) touching the longitudinal inner wall surface (2′) of the housing (2).