Abstract: A hydraulic turbocharger having replaceable, insertable components, including volute inserts, vaned diffuser inserts, nozzle inserts, diffuser inserts, nozzle liners and diffuser liners, that define the internal passageways of a hydraulic turbocharger. By making various components of the turbocharger removably insertable and replaceable, turbochargers can be manufactured in a cost-effective way to maximize efficiency, obtain improved performance and make it easier to operate these types of devices over a wide range of operating conditions. Moreover, the devices can be readily modified while in the field when operating conditions change.