A synchronous electric motor for operating a pump includes a motor body, a stator and a rotor coupled to an impeller of the pump. The motor also comprises a cylindrical element that extends towards the inside of the motor body from one of its outer walls so as to define a first cylindrical cavity open to the outside to insert inside the rotor, wherein the rotor has a circular cross section essentially corresponding to the inner section of the cylindrical element so that the rotor is in contact with the cylindrical element and then there is a friction between the rotor and the cylindrical element when the rotor rotates, and the rotor is shaftless and axially and directly coupled to the impeller of the pump.