They were two goals down inside the first 20 minutes. Albion took the lead on 16 minutes, with Uruguayan centre back Williams Martinez heading home after rising in the six-yard box to get on the end of a Jeff Forsyth corner.
Four minutes later the Baggies doubled their lead, with Stuart Nicholson outmuscling David Edgar to latch onto a pass from Zoltan Gera and fire across Tony Caig into the far corner.
Martin Brittain, who has been involved in first team duties this season, limped off injured in the first half. But Australian defender Craig Moore, recovering from his own injury problems, played out the whole 90 minutes.
WBA RESERVES: Kirkland; Hodgkiss, Kelleher, Davies, Martinez, Forsyth, Gera, Carter, Elvins, Nicholson, Humphrey (Baker 60).
Subs Not Used: Daniels, Sissoko, Pringle, McQuilken.
NEWCASTLE UNITED RESERVES: Caig; Shanks, Farman, Moore, Edgar, Gate, Brittain (Atkin 24), Pattison, O'Brien, Chopra, Cave.
Subs Not Used: Cook, Terrell, Marshall.