Oil transport structure in an electric motor of an electric submersible pump (ESP) assembly

A method of lifting wellbore fluid to a surface, comprising:

• making-up an electric submersible pump (ESP) assembly at a surface location over the wellbore;
• running the ESP assembly into the wellbore at the lower end of a production tubing string;
• providing electrical power to an electric motor of the ESP assembly to cause the electric motor to turn, thereby turning a drive shaft of a seal section of the ESP assembly that is coupled to a drive shaft of the electric motor, thereby turning a drive shaft of a production pump assembly of the ESP assembly that is coupled to the drive shaft of the seal section;
• lifting wellbore fluid to the surface by the production pump assembly;
• and
• moving oil upwards in a bore of the drive shaft of the electric motor that is concentric with a longitudinal axis of the drive shaft of the electric motor, where the oil is moved by a fluid mover disposed within and coupled to the bore, wherein the fluid mover comprises a helical flighting open in the middle.