A diffuser insert is provided for use with a welding diffuser and contact tip assembly comprising a diffuser with an interior chamber configured to receive a wire conduit that supplies electrode wire and a shielding gas used during a welding operation and a contact tip coupled to the diffuser and configured to receive electrode wire. The diffuser insert comprises a diffuser insert body configured to be disposed within the interior chamber of the diffuser, and further comprises an insert bore extending therethrough configured to receive electrode wire. An outer periphery of the diffuser insert has at least one surface feature configured to manipulate a flow of said shielding gas from within said interior chamber of the diffuser and out of exit passages to thereby direct said flow of shielding gas about a molten welding puddle formed during a welding operation.