If the leak is in the lower part, it is most probably due to the rotary joint (mechanical seal). To replace this, you will need to obtain either the seal on its own or the complete joint kit containing all the static connection seals and mechanical seal.
This operation is not complicated but if you are not confortable with DIY tasks, ask your pool installer to do it for you.
However, make sure you do it relatively quickly to avoid permanent damage to the motor.
In most cases, a leak at the seal occurs because the pump has been operating without water. It is fundamentally important for water to always be passing through the pump, especially during priming.