A blood pump comprises a pump housing; a rotor positioned in the housing and comprising an impeller having a hydrodynamic surface for pumping blood; and a motor including a plurality of magnets carried by the impeller, plus a rotor stator, including an electrically conductive coil located adjacent to or within the housing. The impeller comprises radially outwardly extending, bladelike projections that define generally longitudinally extending spaces between the projections. The shape of the projections and the spaces therebetween tend to drive blood in the spaces in an axial direction as the impeller is rotated. The spaces collectively have a total width along most of their lengths at the radial periphery of the rotor, that is substantially equal to or less than the collective width of the projections along most of their lengths at the radial periphery. Thus, the bladelike projections are thicker, achieving significant advantages.