There is provided parts for assembly to produce a flow diverter configured for disposition within a wellbore. The parts include an insert-receiving part including a passageway, and a flow diverter-effecting insert configured for insertion within the passageway. The flow diverter-effecting insert is co-operatively configured with the insert-receiving part such that a flow diverter is defined while the flow diverter-effecting insert is disposed within the passageway. The flow diverter is configured for: receiving and conducting a reservoir fluid flow; discharging the received reservoir fluid flow into the wellbore such that gaseous material is separated from the discharged reservoir fluid flow within the wellbore, in response to at least buoyancy forces, such that a gas-depleted reservoir fluid flow is obtained; and receiving and conducting the obtained gas-depleted reservoir fluid flow.