Striker Aspas arrives from Celta Vigo with a reputation as a determined competitor, whilst fellow forward Luis Alberto impressed for Barcelona B last season.
"When we sat down last year we felt we needed to bring more of that mentality into the group - players with quality but also players with a winning mentality," Rodgers told the club's website.
"Iago is a real competitor but he's also got quality as well. We're really looking forward to seeing him in action.
"(Luis) is one who, over the next period of time, we'll see is an outstanding player. He fits what we're trying to do really well.
"He's a very young player but he's played competitive games, and the philosophy won't be anything new to him.
"He understands the game very well. He's got the right profile of what we want and he's another player who can score goals.
"I'm very much looking forward to working with him and seeing how he develops in the squad.
"There's no pressure. You saw with Philippe Coutinho, who came in at the beginning of the year at 20 years of age, and he was a similar profile - had experience but was young. He set the Premier League alight in his first six months here.
"Luis is big as well and hopefully he can produce for us like many of the Spanish players have done over the years."