Ojomoh only came into the starting team as a late replacement at inside centre after the injured Fraser Dingwall was ruled out on Friday.
But the 25-year-old Bath back, in just his second Test appearance, produced a man-of-the-match performance, scoring England's first try and creating their other two in a 27-23 win over the Pumas at Twickenham on Sunday.
Ojomoh's display has left Borthwick with a selection dilemma ahead of England's Six Nations opener against Wales on February 7.
"A year ago people were going crazy about a centre crisis," said Ojomoh after England completed a November clean sweep.
"Now I'm seeing Seb (Atkinson), Fraser, Ollie Lawrence, Luke Northmore and a lot of 12s coming through and that kind of competition pushes everyone to perform at a higher level.
"Seb and Fraser have been excellent in their last games at 12 so I thought I had to try something out there."
Ojomoh, the son of former England flanker Steve Ojomoh, added: "Only the lucky ones and the very, very good players get picked straight away, play well and keep their spot.
"It's a very competitive position so there are a lot of contenders up there for one position on the field. If you are in form, you keep going."
Ojomoh opened the scoring with a well-taken score in the 10th minute and set up tries for Immanuel Feyi-Waboso and Henry Slade.
Feyi-Waboso was the grateful recipient of a superb cross-kick from Ojomoh, the Exeter wing caught the ball without breaking stride before sprinting across the line, while Slade benefited from his centre partner's hard run and flipped back-of-the-hand pass to score a key try.
"My favourite bit was the cross-kick because I have never done that in the Prem," said Ojomoh.
"I have tried when I've had a penalty advantage and I have spooned all of them, so it was a great time for it to stick. And to kick it to a very good friend in Manny - I'm glad he got the try.
"I was really surprised by the offload. I saw Sladey, and I was 'nothing to lose, may as well have a crack'.
Victory over Argentina was England's 11th win in a row and they now enter the Six Nations as title contenders.
"I'm very happy for the team that they have got four from four this month," Ojomoh said. "It's a great note to end on.
"It's been a very good campaign from a very well-gelled squad. It's good to be a part of."