An electric pump assembly includes in sequence: a wet section, an air gap sleeve containing the rotor of an electric motor, and a casing which contains the stator of an electric motor. The electric pump assembly further includes a box, which contains an electronic board- and has a tubular body for the insertion of a plug for access to the wet section. The casing is substantially concentric to the air gap sleeve. The box is constituted by a tray which is closed hermetically by a lid.