The visitors went into the match without a league triumph in any of their last three matches, but an away victory rarely looked in doubt and came away with all three points.
Armenteros netted Willem's first after just six minutes, putting rock-bottom Dordrecht under pressure early on with a clever finish from a tight angle.
The away side doubled their lead just ten minutes later as former Chelsea and Portsmouth youngster Ben Sahar steered home from close range after good work from Bruno Andrade.
Armenteros scored his second of the game with an easy tap-in after 55 minutes, taking his tally to eight goals in 10 league starts this season.
And Terell Ondaan then gave the scoreline a more resounding look in the fourth minute of second-half stoppage time, stabbing home from five yards following Robert Braber's header into the danger area.
