Gerrard played a part in Joe Allen's opener at Anfield, with club legends Robbie Fowler and Jamie Carragher making cameo appearances as second-half substitutes.
"He's (Aspas) got that little bit of magic and he will certainly strengthen the squad," Gerrard told Sky Sports News following his testimonial that celebrated his 10 years as club captain.
"You can see the talent there. Kolo Toure was very assured at the back and it was another clean sheet for [Simon] Mignolet.
"Luis Alberto is one for the future. I'm sure every minute he gets here at Anfield it'll be a great experience for him. All our new signings are settling well."
Olympiacos were chosen as Liverpool's opponents due to Gerrard's spectacular goal against the Greek side in the 2005 Champions League campaign, which kickstarted the club's fifth European triumph.