Artemyev, who scored a try against Ireland in the recent World Cup, grabbed two more on Saturday to take his tally to six from three matches since arriving at Franklin's Gardens.
Mallinder said: "He's settled in really well and seems to know the way to the try line.
"He'd stood out playing for Russia who were not always winning games and getting on the front foot, but he had the knack of scoring and looking good."
The 24-year-old had three years playing for University College Dublin before returning home to play in Russia and Mallinder added: "It helped with him speaking English, having played in Ireland."
Northampton have now won four matches in succession sine their players began returning from the World Cup and Mallinder said: "We scored some good tries in the second half.
"It was a difficult first half, Newcastle put us under pressure and we knew that, with Jimmy Gopperth's boot, we couldn't give away penalties."
Former Newcastle player Tom May scored the first two Saints tries against his former club in the opening half, with England winger Chris Ashton adding the final two late on.
"I think Tom was determined to do well against his old club but Chris's tries were just a bonus. All the hard work was done up front before that," Mallinder added.
Newcastle head coach Alan Tait said: "At half-time the changing room was happy but I warned them they were playing a very good Northampton team.
"We started the second half really poorly and you could see the heads going again. We're at the bottom and it doesn't take a lot to see their heads go, but they are a good set of lads."
Injury-hit Newcastle are at home to promoted Worcester on Friday night and Tait added: "We've got to keep in the pack so next week is important for us.
"We've had horrendous injuries with a lot of good players missing for the season so far, but I'm pretty confident that when we get these players back we'll kick on and shock a few people."
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