The invention concerns an AC electric motor (1) comprising a stator magnetic circuit including a first part (2) whereon are mounted electrical windings (7 and 8) and a second recessed part (10) wherein is mounted a rotor (14). The invention is characterized in that the first part (2) of the stator magnetic circuit and the electrical windings (7 and 8) are mounted inside a stator chamber (20) with sealed wall, the second part (10) of the stator magnetic circuit, the cylindrical rotor (14) being located outside said chamber. The invention is applicable in the oil industry for pumping fluids in bottom holes producing hydrocarbons in liquid, gas or polyphase form and in chemical and nuclear industries for pumping dangerous or chemically harmful fluids.