If you have a dollar store near you, see if they have any cigarette lighter plug to USB charger adapters. You are nearly 100% guaranteed that it'll have a MC34063A buck regulator in there. Complete with schottky diode and coil.
Many of the cigarette lighter plug phone chargers also use the MC34063A chip.
The Dollar Tree here has them now and again, and the ones they sell use a rewindable inductor and the chip itself, the diode, and inductor are through-hole components. You'll have to replace the input caps to withstand 24V (use 35V capacitors) and change some other components.
This chip has a built-in current limiter, it can output a maximum of 750mA. However! You should not be daisy chaining regulators. The LM317 in your circuit, besides having insufficient input smoothing capacitance, has to carry all the circuit current. You never said, what is the input voltage there? Is it AC, or is the bridge rectifier there just so it doesn't matter which way a battery is connected? Either way, there should be more capacitance there.
The MC34063 can withstand up to 40V of input voltage.