Langer's side secured their spot in the last four with a 64-run win over hosts England at Lord's on Tuesday and return to the famous north London ground on Saturday to face neighbours New Zealand in their penultimate round-robin tie.
With the Ashes test series in England to come after the World Cup, Australia might be forgiven for giving the pace duo a rest but Langer said the players would probably not want to put their feet up at any stage of the tournament.
"I would be surprised if either of those guys rest up," Langer told a news conference.
"The challenge is going to be that we have long layoffs now, a bit of a layoff here, then five or six days in Manchester, we have to manage that really well. So I don’t think they will want to rest."
Left-armer Starc is the top wicket taker at the World Cup so far with 19 from seven matches and while Cummins started well with 11 from his first five matches, he drew blanks against Bangladesh and England.
Langer said he was not concerned at all with the 26-year-old's form.
"He hasn't got the wickets in the last two games, but he's still been a huge part of our side," Langer added.
"He's someone who's so reliable that you go to when you either need a wicket or you need some control in a game. He provides so much for the side."
Both pacemen were put into the shade a little on Tuesday, however, when Jason Behrendorff took five for 44 after bowling James Vince through the gate for a duck with the second ball of the England innings.
"To come to England and bowl on the big stage as well as he did, it will be a great confidence boost for him," said Langer, who coached the left-arm seamer at Western Australia.
"I've seen it for a long time ... he is a very good athlete and he's an incredible professional so he will do everything possible to play.
"And he's a really nice person. To see those sort of people get a reward is really pleasing."
(Reporting by Nick Mulvenney in Sydney, editing by Peter Rutherford)
