Old picture posted long ago and debunked.
Stealth aircraft need to be designed from the ground up as such to achieve optimal LO effectiveness.
Just replacing metal parts with composites could have the opposite effect of reducing RCS if that allows incoming radar to hit more reflective surfaces inside the airframe.
The time, effort and money needed to make JF17 LO would be comparable if not on par with designing a medium weight stealth fighter form scratch.
And even if you manage it, you still cannot get away from physics, so you would end up with a JF17 stealth that has really limited internal weapons load and/or very poor range because it is sacrificing significant internal volume for weapons bays at the expense of fuel.