Ms Suriyapperuma tells BBC News she was "shocked" at negative reactions the photos initially generated. "I was genuinely baffled at why these people would spend their valuable time hating someone they don't even know," she says.
The women found themselves being cyber-bullied and body-shamed. But then, people - including many strangers - started taking on the trolls.
One even tweeted an image of the two women attending Lanka Comic Con, held in Colombo last weekend. Twitter user @Pasan_Mathisha encouraged others to retweet the image, rallying the Internet behind the women.
These women cosplayed Wonder Woman at Sri Lanka Comic Con, and now being rediculed on social media. RT if you think they look amazing! pic.twitter.com/0uq5NOsLAI— Mathisha (@Pasan_Mathisha) August 27, 2017
In four days, the image of the two women dressed as the DC Comics heroine has been retweeted over 42,500 times and 'liked' over 60,000 times.
"You're the real thing...You made us all proud," tweeted Wonder Woman director Patty Jenkins.
Both young women tweeted their thanks for the support:
@GalGadot THANK YOU SO MUCH this means the world to us— Seshani (@SeshaniCooray) September 1, 2017
"Amaya and I were very upset and all we could do was report against those social media pages. But we also never expected to receive so much support and for that we are grateful," Ms Cooray tells NewsIn.Asia.
Ms Suriyapperuma tells BBC that, in a way, she's glad the pictures went viral. "If we didn't get this much coverage this would've been just another case of cyberbullying...But now everyone knows it and thus we have opened a very important conversation about bullying and body-shaming."Click for more trending news