A turbine stator vane with cooling air cavities each having an impingement cooling insert secured therein, and an impingement cooling insert secured within each cavity. A leading edge impingement insert and a mid-chord impingement insert have a section on the pressure side wall with impingement holes forming a parallel flow of impingement cooling air and a section on the suction side wall with a sinusoidal shaped piece that forms a series of impingement cooling holes that produces impingement cooling on cooler surfaces of the airfoil but with less cooling air flow.