Abstract: The pump comprises a pump body and a volute complementary to each other which, once assembled, provide a sealed body defining a first chamber, containing a permanent magnet rotor, and a second chamber containing an impeller and provided with suction and delivery conduits. The stator body of the electric motor externally encircles the second chamber, thus never being reachable by the pumped liquid. The rotor and the impeller are kept coaxial to one another by centering means and have engagement elements which reciprocally connect them in the rotation.