A turbine nozzle segment includes: an arcuate outer band segment; an airfoil-shaped turbine vane extending radially inward from the outer band segment, the turbine vane having a hollow interior; an impingement baffle assembly secured to the outer band so as to define an impingement cavity in cooperation with the outer band segment, wherein the impingement baffle assembly has at least one impingement hole formed therein which is arranged to direct cooling air at the outer band segment; and at least one impingement insert having at least one impingement hole formed therein disposed in the interior of the turbine vane, the impingement insert mating with an opening in the impingement baffle assembly such that the impingement baffle is isolated from direct fluid communication with the impingement cavity.