submersible pumps are vertical, multi stage, centrifugal pumps with motor at the bottom & pump at the top. The water enters at the bottom of the pump and flows upwards through many stages.
The stainless steelbronze impellers rotate inside the diffusers with inherent guide vanes. The diffusers direct water leaving each impeller towards the suction opening of the next impeller. Such a flow through each stage of impeller and diffuser combination adds pressure at each stage and finally water under high pressure is discharged through outlet at the top.