There is disclosed a modular, linearly actuated high-pressure pump for use in various applications with high-pressure fuel systems, in particular liquid cryogenic fuels such as Natural Gas, Hydrogen, Nitrogen and Argon (LNG/LH2/LN2/LAR). The pump utilizes linear actuation which smooths out the power profile. There are no dynamic seals which prevents failure from leakage. The primary benefit of a smooth, no pulse output and lack of dynamic seals is a longer life of the pump. Marine fuel systems that utilize cryogenic LNG are a primary application.