Twenty-year-old Insua has been first choice at left-back this season, starting every Premier League and Champions League match.
Having started to fulfil the promise which persuaded Benitez to sign him permanently from Boca Juniors in August 2007 - he was previously on loan as a 17-year-old - he has now attracted the attention of Argentina boss Diego Maradona.
"It is very good news for him and for us," said Benitez on Insua's selection for crucial World Cup qualifiers against Uruguay and Peru.
"He is a young player who is doing well for us. When you talk about young players, the idea is to try to promote them.
"Emiliano was a very good signing by our scouting department - a young player with potential and quality - and it was very good business because the price was good.
"Last year we had three or four clubs asking about him. But we said 'no', because we want to keep him."