An irrigated needle electrode ablation catheter has a distal tip section with a tip electrode, a needle electrode assembly longitudinal movable relative to the catheter, and a needle centering insert in a channel in the tip electrode. The assembly has a proximal tubing and a distal needle electrode, and the insert supports the needle electrode in the channel at a predetermined separation distance from the tip electrode while enabling irrigation to flow circumferentially around the needle electrode through the channel and exit at the distal end of the tip electrode. The catheter also provides a first dedicated fluid pathway through the assembly and exits at the distal end of the needle electrode, and a second dedicated fluid pathway to supply fluid to the channel in the tip electrode, wherein the second pathway is defined by a guide tube and directed by a plunger member.