A pump for immersion in a fluid includes—an inductor having guide vanes to induce linear fluid flow； —a rotor with a central, flared body, this rotor being downstream of the inductor relative to the direction of fluid circulation； —a helical blade provided around the central body； this helical blade having a flared external profile and having turns with an increasing winding pitch, and the internal casing volume being complementary to the flared helical blade, —a casing around the rotor； —a diffuser having blades making the flow of fluid linear and disposed downstream of the rotor to evacuate the fluid from the rotor； and—a diffuser insert having blades and an outlet orifice with a diameter less than the inlet diameter of the diffuser insert, the blades directing the fluid from the diffuser towards the orifice to increase the orifice outlet pressure.
