Abstract: A hydrodynamic pump comprising a casing in which a shaft having a plurality of spaced impellers is mounted. The casing is formed with diffuser channels interposed between successive impellers. Each diffuser channel comprises a curved section communicating with the outlet of one impeller and an axially-radial centripetal guide channel having a plurality of vanes located therein. Each of the vanes has a curved pressure face and a curved suction face. The angles of inclination of the curvature of the pressure and suction faces at the inlet end of the vanes are both within the range of 5.degree. to 30.degree.. The angle of inclination of curvature of the outlet with respect to the suction face of the vane is within one 100.degree. to 130.degree. and the angle of inclination of the curvature of the outlet with respect to the discharge pressure face is between 60.degree. to 90.degree..